The Bitcoin network processed its first quantum-resistant mainnet transaction on August 26, 2026, recorded in block 964,199. The execution operated under existing consensus rules without requiring a soft fork, new opcodes, or node modifications.
Dubbed Quantum-Safe Bitcoin (QSB) and designed by StarkWare researcher Avihu Levy, the transaction entered the blockchain via MARA Pool’s Slipstream service. A direct path to miners was required because standard nodes classify QSB as a non-standard transaction format and refuse to relay it through the public mempool.
The computational cost for this extra security reached $150 to $200 in GPU usage, taking several hours to compute because each transaction demands roughly 2^46 hashing attempts.
Relying on RIPEMD-160 Without a Soft Fork
QSB’s security relies on the preimage resistance of RIPEMD-160, offering roughly 118-bit strength. This method bypasses Bitcoin’s default elliptic curve cryptography (ECDSA), which remains vulnerable to quantum decryption. StarkWare CEO Eli Ben-Sasson noted that the QSB innovation provides early assurance that asset ownership can be safeguarded before large-scale network upgrades are formally deployed.
However, technical limitations constrain this early solution. QSB functions only for pre-SegWit legacy scripts and offers no protection for Taproot outputs or Lightning Network channels. Levy himself views his innovation merely as a last-resort emergency measure rather than a full-scale protocol replacement.
Dormant Coins Remain Vulnerable
Expert Daniel Batten cautioned that claims of QSB making Bitcoin quantum-proof are overstated. The key requirement is that assets must be moved to a QSB output before quantum attackers emerge. If an address’s public key has already been exposed on-chain, QSB cannot help, leaving dormant coins held there at risk.
In March 2026, Google released estimates indicating that a sufficiently powerful quantum computer could derive a Bitcoin private key within 9 to 12 minutes once the public key becomes visible.
Long-Term Solution Options
Blockstream is taking a different approach with its published SHRINCS proposal. As the first post-quantum signature scheme designed specifically for Bitcoin, it ranges in size from 548 to 4,619 bytes - a significant jump from Schnorr’s current 64-byte size. The proposal, currently being tested on the Liquid sidechain, is estimated to maintain Bitcoin’s throughput at around 3 transactions per second (TPS), compared to 0.36 TPS using NIST’s SPHINCS+ standard, though SHRINCS has yet to include a formal security proof.
Bitcoin developers are also weighing the BIP-360 proposal based on Pay-to-Merkle-Root, an approach that would require fundamental base-layer protocol changes.
The threat of quantum attacks is no longer just an academic debate on cryptography forums, but is already driving real-world blockchain experiments with measurable price tags. Reported by crypto.news.
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Disclaimer: This article is for informational and educational purposes only, not financial advice. Cryptocurrency assets are highly volatile and carry significant risk. Always do your own research (DYOR) and never invest more than you can afford to lose.
